Hair loss can also result from being UNDERtreated...not being at the right TSH, or not taking the right drugs for you. An increasing number of doctors believe that a TSH of around 1 - 2 is optimal for most people to feel well and avoid having hypothyroid or hyperthyroid symptoms such as hair loss. (Note that these levels are kept lower for thyroid cancer patients to prevent cancer recurrence.) To understand UNDERtreated hypothyroidism better, you may want to read my book Living Well With Hypothyroidism, which looks at your next steps -- including defining the "normal" range with your doc, antibody testing, TRH testing, and drugs beyond T4 therapy -- and where to find a doctor to help.
Find Out if You Need a Second Drug
I am one of the people who does better and has less hair loss on a T4/T3 drug versus pure synthetic T4 only (like Synthroid.) Having both T4 and T3 has worked far better for me than levothyroxine. Some studies have shown that a subset of patients feel and do better on a combination of T4 and T3, not T4 (i.e., levothyroxine drugs like Synthroid) alone. For me, the addition of T3 helped relieve depression, brain fog, fatigue and other symptoms. This information about T3 is groundbreaking and has major implications for people who don't feel well on their current thyroid therapies!!! Hair loss and restoration takes place over a longer time frame than this study looked at, however, I wouldn't be surprised if it too was affected positively by the addition of T3. It certainly proved to be the case for me personally.
Consider an Alternative Treatment
When I have had major bouts of hair loss (despite low normal TSH and being on a T4/T3 drug), I took the advice of a doctor I interviewed for my book, Living Well With Hypothyroidism. Here's an excerpt from the book:
. . . evening primrose oil (also known as EPO) is a nutritional supplement that is frequently mentioned. In his book, "Solved: The Riddle of Illness," Stephen Langer, M.D. points to the fact that symptoms of essential fatty acid insufficiency are very similar to hypothyroidism, and recommends evening primrose oil -- an excellent source of essential fatty acids -- as helpful for people with hypothyroidism. The usefulness of evening primrose oil, particularly in dealing with the issues of excess hair loss with hypothyroidism, was also reinforced by endocrinologist Kenneth Blanchard. According to Dr. Blanchard:
"For hair loss, I routinely recommend multiple vitamins, and especially evening primrose oil. If there's any sex pattern to it -- if a woman is losing hair in partly a male pattern - -then, the problem is there is excessive conversion of testosterone to dihydrotestosterone at the level of the hair follicle. Evening primrose oil is an inhibitor of that conversion. So almost anybody with hair loss probably will benefit from evening primrose oil."
As someone who has had a few periods of extensive hair loss since I became hypothyroid, I can vouch for the fact that taking EPO was the only thing that calmed it down. It not only slowed, then stopped my hair loss over about two months, but new hair grew back, and my hair was no longer straw-like, dry and easily knotted.